We are @ the final stage of implementing Oracle e-business suit 12 and recently came across a peculiar font mapping problem with custom developed reports. We use both Developer 6i reports developer as well as 10g reports developer.
Once the reports are tested and uploaded to the apps instance, the outputs were always producing gibrish (PDF outputs especially). However after few days of experimenting, finally we found a work around (hopefully)!

Following are the tips:

Design your report, test it.
Do not change the default font until your report is ready to upload to the instance.

Now decide the actual font you need to use with your final report.
And never select the font from the font list drop down, check the image:

Instead click on format menu item, select “font” and choose your font. Generally we use Courier New or Times New Roman (Western) for our reports and this method has solved our months long troubles with the reports. Please check the attached image:

When you need to change the font sizing and weight for individual items, follow the same method and once you are satisfied with the layout upload to the apps instance.
We hope this work around is helpful for few out there.